1. Field of the Invention
The present invention generally relates to tape cassettes and, more particularly, is directed to a tape cassette having stationary tape guides made of polyethylene-based resin.
2. Description of the Prior Art
For example, a tape cassette utilized in a video deck or the like is provided with stationary tape guides which come in contact with a magnetic tape so that the movement of the magnetic tape is stabilized. The stationary tape guides are positioned at opposite ends of a front wall of the cassette casing so that the magnetic tape is extended along the front wall of the tape cassette.
Referring to FIG. 1, which shows an example of a known tape cassette, there is shown a cassette casing 1 which is generally made of acrylonitrile butadiene styrene (ABS) resin. A pair of tape reels 2 are rotatably provided within this cassette casing 1. A magnetic tape 3 is supplied from one tape reel 2, contacted with and guided by a tape guide 4, withdrawn to the outside of the front wall of the cassette casing 1, contacted with, guided by the other tape guide 4 and is then taken up by the other tape reel 2.
The tape guides 4 provided in the tape cassette are formed so as to come in contact with the rear surface of the magnetic tape (i.e., tape base side) and the tape guides are unitarily formed with the cassette casing or the tape guides are made of a plastic material (see Japanese Patent Laid-Open Gazette No. 61-110388) or made of metal and are inserted into and secured to the inside of the cassette casing.
Further, Japanese Patent Laid-Open Gazette No. 55-70976 describes such a tape cassette in which there are used as the tape guides rollers made of polybutylene terephthalate (PBT) resin.
Most of the stationary type tape guides of the prior-art tape cassettes are made of metal because the metal tape guides are relatively low friction, long wearing, and have high durability compared to the magnetic tape. In that case, however, from the very nature of the metal material, the end face of the tape guide or the cylindrical face of the tape guide must be finished by a mechanical finishing-process. This brings about the following shortcomings and disadvantages:
1. The tape guides become very expensive;
2. A highly sophisticated technique is required to increase the accuracy in the surface-finishing process thereof. That is, if the surface of the tape guide is made too smooth, then electrification occurs, due to the build up of a static charge, to electrically attract the magnetic tape to the tape guide. Conversely, if the surface of the tape guide is too rough, the magnetic tape will be frequently damaged due to friction with the tape guide; and
3. If a convex shaped scratch occurs on the surface of the tape guide, the material of the tape guide is hard so that the magnetic tape will be damaged considerably. That is, it becomes very important to inspect the tape guides as products.